[0001] The present invention relates to stirrers for machines for making ice cream or the
like.
[0002] The prior art includes many types of stirrer for ice cream-making machines, which
adopt a variety of different mechanical principles. Generally speaking, the stirrer
assemblies of such machines comprise a plurality of stirring means, which may be flat
blades or helical blades, some also being capable of scraping the inside surface of
the chilling chamber of the ice cream machine, and these are connected to a rotary
drive shaft which in turn is connected to drive means. The connection between these
blades and the shaft may be achieved in a variety of ways, for example by means of
a frame, usually of metal, connected to said shaft and designed to support the stirring
and scraping means as reported in EP-A-0497336 .
[0003] However, such a construction would certainly be somewhat heavy, given the large quantity
of metal parts; and besides this, the great number of parts of which the frame is
made makes the structure complex, difficult to fit, service and clean, and therefore
liable to present a health risk.
[0004] European Patent Application No. 93111578.6 discloses a stirrer in which the helically-shaped
blades are made of plastic and constitute the largest part of the stirrer, and said
stirrer comprises a drive shaft, a plurality of radial screws mounted equidistantly
on said shaft by means of one end, and a screw-connecting hub to which the screws
are fixed at the opposite end from the shaft. This stirrer also has scraper means
mounted on said screws.
[0005] Such a device has great advantages over the prior art; however, the scraper means
are inserted onto the stirrer blades and have thrust means to ensure that they contact
the inside surface of the chilling chamber. They are therefore still decidedly complicated
in construction. Moreover, in this stirrer the fastening means are housed in holes
formed in said screws, which are then stopped up with plastic inserts; this makes
for a real risk from the hygiene point of view, quite apart from the obvious complications
of construction.
[0006] It is an object of the present invention to provide a stirrer that combines the utmost
mechanical simplicity with the utmost hygiene. In addition, another object of the
invention is a stirrer that has scraper means formed in the simplest possible manner
on said stirrer blades.
[0007] The subject of the present invention is therefore a stirrer for machines for making
ice cream or the like, comprising:
a section of a rotary drive shaft;
a first hub supporting a plurality of angularly equidistant radial spokes integral
with the drive shaft section;
a second hub supporting the same number of spokes as the first hub;
which spokes of said second hub are provided at their ends with fastening components,
and said first hub contains radial passages that extend, from a position diametrically
opposite said spokes, axially through them, to accommodate pin-type fastening means;
and a plurality of stirrer blades provided at their axial ends with holes having means
for engaging said fastening means of said first and second hubs.
[0008] Advantageously, said stirrer blades are made of plastic.
[0009] A further subject of the present invention is the fact that said stirrer comprises
scraper means formed integrally with the stirrer blades themselves, so that said blades
have no additional holes, inserts or moving parts.
[0010] Another subject of the present invention is the method of assembling stirrers of
the type described above, comprising the following steps: the stirrer blades are fastened
to the ends of the radial spokes of the second hub; and the opposite ends of said
blades are fastened to the first hub, which is integral with the drive shaft section,
by inserting the fastening means into the radial passages inside said hub, said passages
being sealed with suitable inserts.
[0011] Other advantages and features of the present invention will become clear in the following
description of an embodiment thereof, given, purely by way of example and without
implying any limitation, with reference to the accompanying drawings, in which:
Figure 1 is a side elevation of the stirrer according to the present invention;
Figure 2 is a sectional view on the plane marked II-II in Figure 1; and
Figure 3 is a sectional view on the plane marked III-III in Figure 1.
[0012] In Figure 1, 1 denotes the drive shaft section of the stirrer according to the present
invention. This shaft section 1 has a square shaft end 201 which fits into a suitable
recess to connect the shaft to the drive means provided in an ice cream-making machine
(not shown). At the other end, the section 1 terminates in a hub 101 from which the
spokes 111 radiate; each of said spokes 111 is connected, in a manner described below,
to one end of each of the helical stirrer blades 2, which are preferably made of plastic.
These blades 2 comprise a blade portion 102 towards the interior, and a scraper component
4 towards the exterior, of the stirrer. This scraper component 4 is formed integrally
with the blade portion 102, and connected to it by the bridges 104. The scraper component
4 has two large through cavities 304, whose purpose will be described later: these
are ellipsoidal and each pass through it occupying about half its length. On the outer
edge of the scraper component 4 are scraper projections 204. At the far end of each
blade 2 away from the end connected to the hub 101 integral with the shaft section
1, said blade 2 is connected to a spoke 103 mounted on a second hub 3, in a manner
described later.
[0013] Figure 2 is a sectional view of the stirrer of the invention. The blade 2 contains
a tapped hole 302 into which the threaded end 113 of the spoke 103 radiating from
the second hub 3 is inserted.
[0014] Figure 3 is a similar view to the previous one and relates to the first hub 101 situated
at the end of the drive shaft section 1. This hub 101 has three radial spokes 111;
inside the hub, through holes 121 run diametrically through said hub 101 as far as
the spokes 111 where they lead into the holes 131. The blade 2 contains, inside the
spokes 111, tapped holes 402 into which the fastening means, in this case screws 401,
are inserted after being introduced through the holes 121 and 131. The holes 121 are
closed by the inserts 301.
[0015] The operation of the stirrer according to the invention and its method of assembly
will be clear from the following. At the moment of assembling the stirrer, the manufacturer
screws the blades 2 onto the spokes 103 of the second hub 3, inserting the threaded
ends 113 of these spokes into the tapped holes 302 of the blades. At the end of this
operation, the holes 402 at the opposite end of the blade 2 will be over the holes
131 formed in the spokes 111 radiating from the hub 101 of the shaft section 1. The
manufacturer then inserts the fastening screws 401 into the holes 121 and, by screwing
them home between the through holes 131 of the arms and the holes 402 of the blades,
connects said parts together. After the parts have been fastened together, the holes
121 are closed off by means of the inserts 301.
[0016] The scraper components 4 are formed integrally with the blades 2. These scraper components
4 perform their function by rubbing against the inside surface of the chilling chamber
of the ice cream machine with their scraper projections 204. These scraper components
4 are supported elastically, by virtue of the cavities 304 formed within them, on
the blade portion 102 via the bridges 104. Advantageously, the scraper projections
204 are arranged on the edge of each scraper component 4 in such a way that they are
staggered from one blade to the next, thus enabling the whole of the internal surface
area of the chilling chamber to be scraped.
[0017] In the stirrer constructed in this manner, the fastening means that used to be used
to connect the blades to the second hub are simply dispensed with and replaced by
the threaded ends of the spokes of the hub itself. This, together with the fastening
system adopted for the connection of the blades to the hub on the shaft section, makes
assembly extremely simple and the stirrer safer from the point of view of hygiene.
Furthermore, the integrally formed scraper means provide a further simplification
of the construction and a further increase in hygiene.
1. Stirrer for machines for making ice cream or the like, characterized in that said
stirrer comprises:
a section (1) of a rotary drive shaft;
a first hub (101) supporting a plurality of angularly equidistant radial spokes (111)
integral with the drive shaft section (1);
a second hub (3) supporting the same number of spokes (103) as the first hub;
which spokes (103) of said second hub (3) are provided at their ends with fastening
components, and said first hub (101) contains radial passages (121) that extend, from
a position diametrically opposite said spokes (111), axially through them, to accommodate
pin-type fastening means (401);
and a plurality of stirrer blades (2) provided at their axial ends with holes having
means for engaging said fastening means of said first and second hubs.
2. Stirrer according to Claim 1, in which said fastening components of the spokes of
said second hub (3) and said fastening means of said first hub (101) are of the screw
type and said holes in the stirrer blades are tapped.
3. Stirrer according to Claim 1 or 2 in which said stirrer blades (2) are made of plastic.
4. Stirrer according to Claim 3, characterized in that said stirrer comprises scraper
means formed integrally with the stirrer blades themselves.
5. Stirrer according to Claim 4, in which said scraper means consist of the scraper components
formed integrally with said blades and connected to them by bridges, said scraper
components having large axial through cavities and having scraper projections on their
outer edges.
6. Stirrer according to Claim 5, in which said scraper projections are in a staggered
arrangement on the outer edges of the scraper means of the different stirrer blades,
so as to scrape the whole of the internal surface area of the chilling chamber.
7. Method of assembling a stirrer of the type indicated in the foregoing claims, comprising
the following steps:
the stirrer blades are fastened to the ends of the radial spokes of the second hub
(3);
and the opposite ends of said blades are fastened to the first hub (101), which is
integral with the drive shaft section, by inserting the fastening means (401) into
the radial passages inside said hub, said passages being sealed with suitable inserts
(301).